1. Field of the Invention
The present invention relates to drug delivery inhaler devices, such as pressurised metered dose inhaler (pMDI) devices and dry powder inhaler (DPI) devices and adapters for fitting to such drug delivery inhaler devices. The invention also relates to methods of operation of such devices and adapters. Of particular interest in this invention is the provision of means for improving patient compliance with such devices.
2. Related Art
GB-A-2372704 discloses a device, such as a spirometer, for determining the respiratory flow rate of a patient. The device includes two reeds adapted to generate an audible signal at different air flow speeds through the device. The first reed generates an audible signal of a first pitch when the air flow reaches a predetermined minimum. The second reed generates an audible signal of a second pitch when the air flow reaches a predetermined maximum. Thus, the patient is informed when the air flow is within a desirable range, between the predetermined minimum and maximum.
Lavorini et al (2010) [F. Lavorini, M. L. Levy, C. Corrigan and Graham Crompton, “The ADMIT series—issues in inhalation therapy. 6) Training tools for inhalation devices” Primary Care Respiratory Journal (2010) 19(4) 335-341] set out a review of training tools for inhalation devices, including the device disclosed in GB-A-2372704, referred to as the “2Tone” trainer. Such a trainer is intended to be used only as a training device and never itself as a drug delivery device.
Lavorini et al (2010) comment that two of the most critical patient errors in the uses of pMDI devices are a failure to coordinate inhalation with actuation of the device and inhaling the aerosolized drug too quickly. The full potential of the drug then cannot be realised.
Lavorini et al (2010) review various other inhaler training devices of different degrees of sophistication. However, each of these devices is a training device, in the sense that a patient uses the training device in order to “learn” an optimum method of using a drug delivery inhaler device. For the simplest devices, once the patient is deemed to have learned the correct technique, the training ends, but there is no ongoing check on whether the patient continues to use the correct technique, over time, with their prescribed drug delivery inhaler device.
Corrigan (2011) [C. J. Corrigan “Asthma therapy: there are guideline, and then there is real life . . . ” Primary Care Respiratory Journal (2011) 20(1) 13-14] and Hardwell et al (2011) [A. Hardwell, V. Barber, T. Hargadon, E. McKnight, J. Holmes and M. L. Levy “Technique training does not improve the ability of most patients to use pressurised metered-dose inhalers (pMDIs)” Primary Care Respiratory Journal (2011) 20(1) 92-96] report on tests of patient compliance using pMDI devices. The tests took place during April-June 2008. The commentary in Corrigan (2011) on the results reported by Hardwell (2011) discusses the fact that 85.6% of 1291 patients tested failed their first assessment of whether they were able to use their pMDI device correctly. This is considered to be a critical issue—incorrect use of a pMDI device based on this assessment means that the drug delivered to the patient is being delivered sub-optimally. In turn, this means that the patient does not receive the correct dose of the drug, which can lead to serious problems in the ongoing treatment of conditions such as asthma. It is considered that such problems remain even when patients have in the past received some training on the correct technique to adopt for using their prescribed drug delivery inhaler device.